The resistance of the second strain to ciprofloxacin and norfloxacin was attributed to active efflux associated with overexpression of gene lde.

In addition to these mechanisms, the presence of an active efflux participating in high-level fluoroquinolone resistance was identified in one strain.

Brivanib showed good brain penetration in rats consistent with its high intrinsic permeability and lack of active efflux in Caco-2 cells.